of the benefits of using a real number as an evaluation measure is that it can help us quickly decide if we need to make some improvements to the algorithm. Increase the accuracy from 99.2% to 99.5%, but does our improvement really work, or do we just replace the code with something like always predicting y=0, so if you have a skew class, using categorical accuracy is not a good way to measure an algorithm, Because you may get a high accuracy, or very low error rate, but we do not know whether
In general, the relationship between recall and precision is as follows:1, if the need for a high degree of confidence, the precision will be very high, the corresponding recall rate is very low, 2, if the need to avoid false negative, the recall rate will be very high, the precision will be very low. on the right, the relationship between recall rate and
Single-precision and double-precision numeric types appear first in the C language (in a more general language), and in the C language, a single precision type is called a floating-point type (float), as the name implies, by floating a decimal point to store the data. These two data types were first created for scientific calculations, and he was able to provide
Due to improper use of float or double, there may be an issue of loss of precision. The problem probably can be understood by the following code : [Java]View Plaincopyprint?
Public class Floatdoubletest {
Public static void Main (string[] args) {
float f = 20014999;
Double d = f;
Double d2 = 20014999;
System.out.println ("f=" + f);
System.out.println ("d=" + D);
System.out.println ("d2=" + D2);
}
}
public class Floatdouble
Often thought to climb the mountains small, can, often and really come to the starting point, Daniel, slowly footsteps to my notes to share it, please~
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This note comes from the CDA-DSC-L2R course. Focus on Precision marketing solutions, marketing portfolio evaluation.
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Practical Problems of precision marketing
Make full use of various
0-1 Predictions for test sets
Accuracy: The forecast pair/total forecast, including 0 of the forecast pair also includes 1 of the forecast pair, usefulness: represents the overall alignment of the model, the higher the model the more accurate
Accuracy: predicted to be 1 accuracy, usefulness: represents 1 of the degree of alignment
Recall: The predicted 1 accounted for the true 1 percentage, use: Represents the forecast 1 coverage
Example:
Now to recommend stocks, analyst A, both want to pre
Division of codevs3118 High-precision exercisesPlayed a high-precision in addition to high-precision, a little excitement inside.Remember when you started to learn it was very difficult to fight#include #include Char s1[600],s2[600];int a1[600],a2[600],a3[600],a4[600],len1,len2,len3,i,j;int bi (int a3[],int a4[]){if (A3[0]return 0;if (A3[0]>a4[0])return 1;for (in
Question B: "High precision" simple high-precision addition
time limit: 1 Sec memory limit: up to MBSubmitted by: 94 resolution: 27Submitted State [Discussion Version]
Topic description Asura King solved the computer's memory limit problem, finally can use the computer for a large magic operation, he handed the Wolf's first task is to calculate two nonnegative integers a, b and, where A and b in th
Ref: http://blogs.lessthandot.com/index.php/DataMgmt/DataDesign/sql-server-precision-and-scale-problems
SQL Server precision and scale problemsby George mastros
24 Nov 2008,Categories:Data Modelling design, Microsoft SQL Server
Specified people are confused about SQL Server's precision and scale. this is unfortunate because choosing the correct values for
确(比如,有的编程语言中提供了专门的货币类型来处理),所以Java使用java.math.BigDecimal专门处理小数精度Constructor Description: BigDecimal(int) 创建一个具有参数所指定整数值的对象。 BigDecimal(double) 创建一个具有参数所指定双精度值的对象。 BigDecimal(long) 创建一个具有参数所指定长整数值的对象。 BigDecimal(String) 创建一个具有参数所指定以字符串表示的数值的对象。usage principle: Initializing decimals must be made with a string, BigDecimal (string), because decimals with double are approximate, not exact values. BigDecimal member Methods add(BigDecimal) 对象自身与参数相加,然后返回这个对象。
Simulates vertical division operations.
VaR S: string; B, M, Len, I, n: longint; A, C: array [1 .. 1000] of integer; begin readln (s); readln (B); Len: = length (s); for I: = 1 to Len do a [I]: = ord (s [Len-I + 1])-48; M: = 0; for I: = Len downto 1 do begin C [I]: = (M * 10 + A [I]) Div B; // record operator M: = (M * 10 + A [I]) mod B; // calculates the remainder end; while (LEN> 0) and (C [Len] = 0) Do Dec (LEN); // remove the first 0 if Len = 0 then write (0) else for I: = Len downt
Float-precision output and floating-point-precision output
The settings related to the output in C ++ are included in the header file "iomanip". First, let's take a look at some functions contained in it:
To retain the N digits after the decimal point and output the result in rounding, setprecision and fixed are required.
// Eg: calculate the area of the circle whose radius is r; output: retain the sev
PHP floating point precision problem summary, php floating point precision. PHP floating point number precision problem summary, php floating point precision 1, PHP floating point precision loss first look at the following code: Copy the code: $ f0.57; echointval ($ f * 100
PHP floating point Precision problem summary, php floating point Precision
I. Precision loss of PHP floating point numbers
Let's take a look at the following code:Copy codeThe Code is as follows:$ F = 0.57;Echo intval ($ f * 100); // 56
The result may be a little unexpected. PHP follows IEEE 754 dual precision:
Floatin
In the actual coding, you will encounter many high-precision cases, for example, in the calculation of money need to retain high-precision decimals, so that the calculation will not be too much error:In the following code, we verify that when the number of two float types is added, the resulting result is error with our expected result, and in order to reduce and prevent this error, we need to use the BigIn
High-Precision algorithm code and high-precision Algorithm
Reproduced from SinGuLaRiTy2001, original link: http://www.cnblogs.com/SinGuLaRiTy2001/p/6591222.html
[SinGuLaRiTy-1001]Copyrights (c) SinGuLaRiTy 2017. All Rights Reserved.Addition:
#includeSubtraction:
#includeMultiplication:
# Include Integer Division:
#includeHigh Precision Non-divisible division for
C ++ addition high-precision algorithms and addition high-precision Algorithms
C ++ high-precision algorithms are a big challenge for beginners. As long as you overcome them, you will start a new chapter in programming, algorithms.
The code I sent is not very good, it occupies a lot of memory and runs for a long time (no more than 1 second), but it is very unders
Examples of common PHP mathematical functions and BC high-precision mathematical functions, high-precision mathematical functions
This article provides examples of common PHP mathematical functions and BC high-precision mathematical functions. We will share this with you for your reference. The details are as follows:
1. Addition of any bcadd precision2. subtract
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